Egg Custard Buns Recipe (Lai Wong Bao)

A while back a young Vietnamese-American woman emailed about how her boyfriend was in love with a particular kind of steamed bao filled with a buttery yellow filling. Did I know how to make them? She would be so thrilled to be able to gift him one of his favorite sweets. I felt like the bao competed with her for his affection. I was compelled to help her but did not have time to until now.

I first thought that the bao was filled with a sweetened mung bean filling, which is buttery and somewhat marzipan like, and directed her to a recipe in Asian Dumplings. No, she replied, the filling that she was looking for tasted eggy.

Then I realized that she was looking for egg custard buns, called lai wong bao (or nai wong bao) in Chinese, which translates into English as "milk custard bun". That awkward name sounds more like a problem spot that needs lots of exercising than a steamed leavened bun filled a rich egg-yolk and sugar filling.

I recently sampled lai wong bao from a San Jose Vietnamese-owned bakery that tasted of egg yolk and a touch of coconut milk. It wasn’t cloying and had a nice richness and touch of tropical Asia. That rendition of egg custard bao got me researching. Today, I made a batch.

Custard Powder and Other Key IngredientsOne of the key ingredients to the filling is custard powder, a popular British baking ingredient that is used in a number of Hong Kong-style sweets. (Hong Kong was a British colony for many years, which explains why the custard powder is popular.) Custard powder is mostly made of cornstarch with some salt, vanilla, and a touch of ground annatto for color. The go-to, popular brand is Bird’s Custard Powder, which you can find specialty foods stores and some Chinese markets.

Vanilla pudding mix is a worthy substitute. I suppose you could also sub plain cornstarch and add ground annatto, but formulating a knock-off version of custard powder was not part of my Sunday morning plans!

Despite the cornstarch in the custard powder, there's lots of additional corntarch in the filling to make it thicken up and cohere. Old fashioned egg custard buns include salted duck egg yolks to lend a savory hit to the sweet filling. I opted to add salt but had a good amount of rich coconut milk. Some cooks use evaporated milk or dry milk powder but I find that sweetened condensed milk lends better depth and flavor. The photo above captures the ingredients that I pulled out for the filling. The rest is egg yolk and butter.

Texture and Tweaking TipsSome renditions of egg custard buns are somewhat runny when you break open the bun whereas others are more solid but very soft. I went for the soft-firm side of things with the filling below. It is easier to shape into a ball and manage as you are encasing it in the dough. That required lots of cornstarch and the filling had a slight starchiness that I didn’t care for. My husband didn’t mind it at all and said, “What needs to be changed? It tastes great!”

Nevertheless, if you want to tinker with the filling, reduce the amount of cornstarch to 2 1/4 ounces, maybe even 2 ounces. Don't worry as the filling will be plenty thick; see the Note on how to handle it if its too soft to shape. After pulling the thickened mixture off the heat, let it cool a tad, taste it, then adjust it. If you want the filling on the runny side, then stir in coconut milk by the tablespoon. If you add too much liquid, recook the mixture to thicken it up. The filling seems to be very elastic, and you can bend it to your will.

So, to the young woman who got me going on making egg custard buns: I hope your relationship is going well and will get even better with homemade lai wong bao!

RECIPE

Egg Custard Bun FillingLai Wong Bao

As with all bao fillings that I make, this one was used along with 1 1/4 pounds of the basic yeast dough on page 92 of the Asian Dumplings cookbook. Follow the instructions for the steamed filled buns recipe (page 95) to shape and cook the buns. For the ones pictured at theh top of this post, I used bleached all-purpose flour for a lighter colored bao dough. The dough and yellow filling of the egg custard bun make it look like a boiled egg!

The amount of filling made here is a little bit less than the usual 1 1/3 cups so you will have extra dough. If you like, twist the extra dough off after you’ve closed the bun up. I made 16 medium buns as they are of moderate size, neither dainty nor gargantuan.

4/22/11 Update: In addition to my comments above, several people have added terrific comments below on adjusting the amount of starch to avoid a gritty finish. Please take a read to help you make an educated guess on how much to use. This filling is relatively flexible so you can play with it.

1. In a saucepan, whisk together the salt, custard powder, sugar, and cornstarch. Whisk in the coconut milk and condensed milk. Heat over medium heat, stirring constantly, until smooth. Add the butter and continue stirring until the butter has melted.

Keep stirring for about 6 minutes, until the mixture has thickened substantially. If it seems hard to stir with the whisk, switch to a spatula. As the mixture stiffens it may look like there are lumps. If you see that, stir more vigorously to break the lumps up and evenly cook. Aim for a smooth texture.

2. When the mixture is thick enough to stick to the whisk and form a soft peak, move the pan off the heat and whisk in the egg yolks. This will thin the mixture out slightly for the moment. Return the pan to the heat and keep whisking to ensure that the yolks are well incorporated.

Continue vigorously stirring for 1 to 2 minutes more, until the mixture thickens to the point where it cleans the sides of the pan and easily comes together as one smooth mass. If you have ever made dough for cream puffs, this is very similar. Stir in the vanilla, then take the pan off the heat. Stir it occasionally for a few minutes to quickly cool it.

At the end, stir the mixture off the heat for a minute and taste it. Make any changes you like at this point, as I suggest above. When you're satisfied, transfer the filling to a bowl, spreading it out.

3. After the filling has cooled, form it into balls.For my 16, each one was about 1 1/4 inches wide, like an extra- large or jumbo egg yolk! Loosely cover and set aside at room temperature, or refrigerate to firm up, until your dough is ready. Then use the balls of filling when you shape the buns. Do the second rise and steam as directed in the steamed filled bun recipe in Asian Dumplings.

NoteShould the filling be too soft after it has cooled, portion it into generous tablespoons, dropping it onto parchment. Loosely cover with plastic wrap and refrigerate to firm up. I found that you can leave it in the fridge until you’re ready to shape the bao. However, a cold filling slows down the second rising so be patient.

Thank you thank you thank you!! Egg custard buns are my favorite and I’ve been dying to try to make them at home. Another version I love is the baked pineapple buns filled with egg custard. I’ll have to try experimenting with this.

My niece’s favorite at the Chinese dimsum near our place is a baked bun with similar custardy filling. Can these buns be baked instead of steamed? Or will that require a different dough? Those buns also have some kind of sugar/flour topping. Does this sound familiar to you?

Hi Andrea!! I’m a frequent reader of your blog and have both your books. I grew up in HK and am soooo excited to see this since we never get things like this in Baltimore. Can’t wait to try it and I second Michelle’s suggestion of egg custard pineapple buns, mmmmm.

Thank you! The only disappointment in Asian Dumplings was not having this recipe. These are one of my all time favorites, and one of the many foods I swore to eat when I visited China in 2009. When making these at home I had previously used the fillings for egg custards in mini-muffin tins. The crustless custard was then spooned into the dough. But the texture was wrong.
It’s the custard powder that’s the key. Thank you so much.

Michelle and Ben: Wow. I glad I’ve completed your Asian dumplings repertoire here.
JessS: I was thinking about the pineapple bun and that requires that crumbly/crusty topping, right?
Lea: Baking these buns require a different dough — the baked bao dough in Asian Dumplings. It’s a dough that has egg in it and more sugar.
Nazneen: LOL. You grew up with Bird’s that’s so great.
P.S. Glad that the spammers here are adding semi-intelligent comments.

Andrea – Tried this with a mix of tapioca starch to cut back on the corn starch. This much corn starch feels gritty on my teeth, especially if it’s not completely cooked. Seemed to work well and the filling was more tender.

Oh my god. :0
Thank you for sharing this recipe! I been looking for this type of bao for ages but wasn’t sure what the name was. 😀 Mum normally makes the traditional Vietnamese style bao with the lap xuong.
I might try making these over the weekend or persuade mum as she’s on a bao making spree at the moment. 🙂

I found an article that suggested substituting tapioca flour 2:1 for cornstarch. Other recommendations were arrowroot and kuzu. I can’t find tapioca flour, so I ground some minute tapioca as finely as I could with a coffee grinder. Wish I had time and resources to make all variations and compare.

I just made the filling today and it tasted very gritty. I didnt like the texture too much plus the ones at the dim sum restaurants taste very smooth. I think i will cut back on the corn starch and see the difference. Did your custard taste gritty too???

Cathy: Thanks. Tapioca flour is the same as tapioca starch. You should be able to get it at health food stores if you’re not shopping at an Asian market.
Vivian: Yep, and I suggested that people play with the starch. We’re all trying to figure out the starch issue. Zach did it successfully but hasn’t revealed his proportions. See what Cathy noted right above your comment. Also see my notes under “Texture and Tweaking Tips” for guidance. Did you lower the amount of cornstarch as I suggested and still got grit? Thanks!
We’ll figure it out together!

Here is what my afternoon’s experiment yielded. I made 2 recipes – cutting the original in HALF. First one was with just cornstarch and yes, the texture is kind of powdery but not as toothy as I was expecting. I overcooked the custard and have hard-boiled “yolks”. However, I don’t live with or around “foodies”, so those who will partake of these will love them and never know the difference. The second recipe (again HALF the original) I made with a combo of 7/8oz cornstarch and 3/4 oz tapioca “flour” that I ground from Minute tapioca using a coffee grinder. It stiffened up in about 2 minutes and has a nice gloss and consistency like slightly runny egg yolk. It looks a little grainy from the ground tapioca and has a somewhat gelatinous texture as you would expect from tapioca. I also used about 1Tbsp more coconut milk. It is very yummy! I will have to try will “real” tapioca flour; the local health food store carries it, kuzu, and arrowroot but they are currently out of stock. I will report later on these thickeners.

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Thank you, thank you and thank you. My little sister, my boyfriend and me love this custard bun so much that we could never have enough of it. I bet they’ll be very happy when I try to recreate this bun. 🙂
When I had this custard bun in Ngan Dinh Restaurant, AnDong Plaza, in Vietnam. The texture of the filling almost like very fine sand, but it melted in the mouth in just seconds. I kinda like that texture for some reason, maybe it’s because it tastes very much like smooth cook salted duck egg.
If I would have use salted duck eggs, do you think I should obmit the salt only?

Hi! I live in a place where the only Bao closest to me are an hour and a half away….I’m completely in love with lai wong bao and I’ve been looking for a proper recipe for ages! This one really takes the cake! I tried searching for it, but I couldn’t figure out how long I’d have to steam them for. Would anybody know?

Just discovered these at Chinese New Year brunch at Asian Jewels in Flushing NY. Me and three friends ordered 3/4 rounds of these, and took 2 orders to go w/us. At first bite we all looked at each other and said, “this is the most amazing thing I ever had!!!” Can’t wait to try making them, thank you for the recipe Miss Andrea. 🙂

Hi Miraa, Not a silly question. This filling is meant to go with the bao dough and instructions in the Asian Dumplings cookbook. See the page reference in the recipe introduction. Here’s info on the book: http://amzn.to/oe3LMK
Thanks!

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Hello, this site was created and maintained by me — Andrea Nguyen. Based in Northern California, I’m a James Beard Award-winning author, freelance writer, editor, cooking teacher, and consultant. Let’s dig in →